2 shaft radio stereo replacement

[John D]

Our 79 came with a non-functioning Blaupunkt, which I removed and saved. 

I installed a JVC two-shaft cassette am-fm that i had lying around ~5 years ago. As of yesterday the AM and the cassette deck still work but no FM. It isn't the antenna.

What's the go-to? I noticed Bob Ziff at avantiparts.biz has Custom Autosound units with Bluetooth and USB but reviews say the Retrosound units are higher quality.

is there a reliable rebuilder for the Blaupunkts?

Hate to hack it up to put a single DIN unit in, but on the other hand it's far from stock anyway...